Tests of Power Corrections to Event Shape Distributions from e+e- Annihilation

TL;DR

This paper analyzes event shape distributions from e+e- collisions at energies 35-183 GeV, testing non-perturbative power corrections and confirming the universality of a key parameter within QCD.

Contribution

It provides the first comprehensive test of power corrections across multiple event shape observables and refines the measurement of the non-perturbative parameter  within the dispersive approach.

Findings

Good agreement between data and combined QCD calculations with power corrections.

Measured  parameter is universal across studied observables.

Revised calculations improve consistency of fit results.

Abstract

A study of differential event shape distributions using e+e- data at centre-of-mass energies of 35 to 183 GeV is presented. We investigated non-perturbative power corrections for the thrust, C-parameter, total and wide jet broadening observables. We observe a good description of the distributions by the combined resummed QCD calculations plus power corrections from the dispersive approach. The single non-perturbative parameter \alpha_0 is measured to be \alpha_0 (2 GeV) = 0.502 +- 0.013 (stat.) ^{+0.046)_{-0.032} (exp. syst.) ^{+0.074}_{-0.053} (theo. syst.) and is found to be universal for the observables studied within the given systematic uncertainties. Using revised calculations of the power corrections for the jet broadening variables, improved consistency of the individual fit results is obtained. Agreement is also found with results extracted from the mean values of event shape distributions.